This invention relates to an apparatus and method for cleaning fabric surfaces. More particularly, the invention relates to a method and apparatus for foam cleaning upholstery fabrics.
Foam cleaning agents have been used to clean fabrics, especially carpets, for many years. While it is possible to perform foam cleaning operations manually, it takes less physical exertion and, therefore, is normally preferable to utilize an apparatus which will assure even application and removal of foam along with moderate agitation of the fabric prior to removal of the foam. Many such apparatus have been attempted to remove the foam as soon as possible after application to prevent overwetting the fabric which can result in shrinkage, browning, mildew, and excessive drying times.
The prior designs included for example U.S. Pat. No. 3,392,418 to Schowalter, which discloses a self-contained carpet cleaning apparatus in which foam is generated through the utilization of a pressurized air stream acting upon a detergent feed tube. The detergent is fed to the tube under the force of gravity. The mixture of the air and droplets of detergent produces a foam. The foam is permitted to drop downwardly from a screen, through slots, onto a cylindrical, rotating brush. The brush is disposed transversely across the apparatus, parallel to the floor, so that the rotation of the brush conveys the foam to the carpet and agitates the carpet. The foam is subsequently removed by a vacuum slot positioned to the rear of the brush.
There are several drawbacks with designs such as those disclosed in the Schowalter patent. First, a heavy, bulky machine is only suitable for cleaning carpets and not upholstery and other fabrics. A second disadvantage, even with respect to carpet cleaning, is that the foam is applied to the fabric (i.e. carpet) by means of the rotating brush, which simultaneously agitates the fabric. Not only are the scrubbing brushes often too harsh on many fabrics, including the pile of standard carpets, but the scrubbing action of the brushes drives dirt particles and the foam down deeper into the fabric making recovery more difficult. The deeply penetrated foam dissipates and makes the fabric wetter. These two conditions result in longer drying times and possible overwetting. Finally, the amount of foam that is applied to the carpet is directly related to the speed at which the operator pushes the machine over the carpet. Thus, it is difficult to ensure that an even and consistent layer of foam is applied to the carpet which may result in uneven cleaning of the fabric.
U.S. Pat. No. 3,751,755 to Smith discloses a hand-held, combination vacuum and foam applicator which also has a number of shortcomings in cleaning upholstery fabrics. First, it does not apply the foam and vacuum simultaneously; rather, the foam and vacuum are independently operated at alternate times. Thus, this apparatus is highly susceptible to overwetting while the foam saturates into the fabric during application. Moreover, in this apparatus, the foam is generated remote from the point of application and must be transported a considerable distance to the applicator. It is inherently difficult to maintain the consistency of foam under transport because it tends to collapse during travel.
Due to the above-described problems in the generation, application, and removal of foam from fabrics, especially upholstery, other cleaning devices have been designed that use liquid cleaning agents. These apparatus are commonly referred to in the industry as "steam" cleaners. For example, U.S. Pat. No. 4,083,077 to Knight et al. discloses a hand tool associated with a steam cleaning machine for cleaning carpets as well as upholstery and other fabrics. The hand tool embodies a generally hollow head defining a cleaning agent chamber with a bottom opening and a vacuum chamber with a bottom opening positioned forward of the cleaning agent chamber. The operator squeezes the trigger to release a fluid solution to the cleaning agent chamber where it is sprayed into the pile of the underlying fabric. As the operator pulls the hand tool in the direction of the cleaning agent chamber, suction from the vacuum chamber is applied to remove the moisture previously sprayed onto the fabric.
One disadvantage of such a steam cleaning system is that the fluid spray exerts virtually no force to the fabric pile to loosen embedded soil to be removed, save for its initial momentum of the spray. Moreover, an inherent problem with steam cleaning systems is overwetting. When cleaning liquid is brushed, sprayed, or otherwise deposited on a fabric, it tends to penetrate deeply into the pile. Once the cleaning liquid has penetrated into the fabric, it is difficult to remove. Also, in passing through the upper layers of the fibers, the liquid tends to absorb dirt and carry it down to the lower layers, where it remains. This minimizes the amount of dirt that can actually be removed from the carpet, and can result in color running, shrinkage, mildew and browning. Another shortcoming of all liquid (steam) cleaning operations is that they require substantial drying times, which is a serious disadvantage, particularly in commercial establishments.
In addition to being subject to all the aforementioned problems of steam cleaning systems, the apparatus disclosed in the Knight patent is also prone to localized overwetting around the edges of an upholstered object. That is, where the liquid spray precedes the suction over the edge of a surface, areas on adjacent surfaces of the object will be wetted but will not be vacuumed.
The present invention responds to the drawbacks and limitations of the prior art by providing a fabric cleaning apparatus which generates foam in one end of the apparatus and directs it toward the fabric to be cleaned. In the preferred embodiment of the invention, the foam is generated by admixing pressurized air and a cleaning solution in the apparatus adjacent to the point of application. The pressurized air also directs the foam towards the fabric. A vacuum is simultaneously provided at the other end of the apparatus, such that it cooperates with the inertia of the foam to move the foam rapidly and continuously between the ends of the apparatus and effectively to produce a continuous belt of foam between the two ends. It is preferred to position a stationary brush between the two ends so that the moving foam passes over and through the bristles of the brush. When the apparatus is applied to a fabric to be cleaned, the foam moves in immediate contact with the fabric, and a partial pressure is created that enhances the agitating action of the foam.
Thus, in the present invention, the rapidly, continuously moving foam, under partial pressure, in immediate contact with the surface of the fabric overcomes many of the disadvantages of the prior art. Specifically, the force of the moving foam erodes and suspends embedded soil instantly, thereby providing improved cleaning. The stationary brush cooperates with the moving foam to further agitate the fabric and foam but without the harsh effect on the fabric of a rotating brush. Moreover, the foam moves rapidly through the horizontal plane of the fabric so that it does not penetrate deeply into the pile of the fabric. This affords easy removal of the foam and minimizes overwetting. Also, a more consistent foam is applied to the fabric because the foam is generated by admixing pressurized air and a cleaning solution in the apparatus adjacent to the point of application.
These and other features and advantages of the present invention will be apparent from the following description, appended claims, and annexed drawings.